Kurt,

Regarding Twain's involvement in simplified spelling --
there are 3 articles from the New York Times dated
March 12, 1906
Sept. 20, 1906
Dec. 10, 1907

The NY Times also ran a letter from Twain pertaining
to his endorsement of the typewriter that Twain
had written on March 19, 1875.  This article from the NYT
is dated Dec. 2, 1923.  However, Twain  doesn't identify
the specific "first" manuscript.

All the articles are available online via:

http://www.tarleton.edu/activities/pages/facultypages/schmidt/nytindex.html

Barb